ide: Initialise buffers with zeros

Just in case there's still a way how a guest can read out buffers when it's not
supposed to, let's zero the buffers during initialisation so that we don't leak
information to the guest.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>

hw/ide/core.c

@@ -1789,9 +1789,13 @@ static void ide_init1(IDEBus *bus, int unit)
     s->unit = unit;
     s->drive_serial = drive_serial++;
     /* we need at least 2k alignment for accessing CDROMs using O_DIRECT */
-    s->io_buffer = qemu_memalign(2048, IDE_DMA_BUF_SECTORS*512 + 4);
     s->io_buffer_total_len = IDE_DMA_BUF_SECTORS*512 + 4;
+    s->io_buffer = qemu_memalign(2048, s->io_buffer_total_len);
+    memset(s->io_buffer, 0, s->io_buffer_total_len);
+
     s->smart_selftest_data = qemu_blockalign(s->bs, 512);
+    memset(s->smart_selftest_data, 0, 512);
+
     s->sector_write_timer = qemu_new_timer_ns(vm_clock,
                                            ide_sector_write_timer_cb, s);
 }